1. Field of the Invention
The present invention relates generally to medical methods and devices. More particularly, the present invention relates to intraluminal catheters with balloons having segments with different material moduli, which upon inflation improve apposition of tools against luminal structures, such as blood vessel walls or walls of other body lumens such as bronchi or the urethra.
Coronary artery disease is the leading cause of death and morbidity in the United States and other Western societies. In particular, atherosclerosis in the coronary arteries can cause myocardial infarction, commonly referred to as a heart attack, which can be immediately fatal or, even if survived, can cause damage to the heart which can incapacitate the patient. Other coronary diseases which cause death and incapacitation include congestive heart failure, vulnerable or unstable plaque, and cardiac arrhythmias. In addition to coronary artery disease, diseases of the peripheral vasculature can also be fatal or incapacitating. Vascular occlusions, blood clots and thrombus may occlude peripheral blood flow, leading to tissue and organ necrosis. Deep vein thrombosis in the legs can, in the worst cases, require amputation. Clots in the carotid artery can embolize and travel to the brain, potentially causing ischemic stroke. Diseases causing narrowing of a lumen in the body are not limited to blood vessels. As examples, but by no means limiting, chronic obstructive pulmonary disease (COPD) and cancerous tumors may cause constriction of bronchi in the lungs, and prostate cancer or benign prostatic hyperplasia (BPH) may cause constriction of the urethra.
Percutaneous or endoscopic interventional procedures are very common in the United States and other countries around the world. Intravascular catheter systems are used for procedures such as balloon angioplasty, stent placement, atherectomy, retrieval of blood clots, photodynamic therapy, and drug delivery. All of these procedures involve the placement of long, slender tubes known as catheters into arteries, veins, or other lumens of the body in order to provide access to the deep recesses of the body without the necessity of open surgery.
Percutaneous procedures also include those that place working ends of catheters into body cavities such as the ventricles or atria of the heart. The placement of needles into the heart wall from within a ventricle can also be performed during catheter-based procedures as described in the previous paragraph.
Medical devices used in catheter procedures often include a working component at or near the distal (farthest from the operator) end of the catheter that is operated by hydraulic, pneumatic, or other mechanical means. These systems can sometimes include a working component such as a microneedle on one side of the catheter or at the distal end of the catheter that must be apposed against the wall of the lumen.
Such catheters can also benefit the treatment of other lumens in the body. For example, the sinus passages leading from nasal openings to the sinuses or pharynx may become inflamed, for example after sinus surgery or in the case of nasal polyposis. In these cases, systems similar to those used in percutaneous procedures may also require apposition of one side of the working end against the lumen wall.
Of particular interest to the present invention, catheters carrying microneedles capable of delivering therapeutic and other agents deep into the adventitial layer surrounding blood vessel lumens have been described U.S. Pat. No. 6,547,803, issued on Apr. 15, 2003, and in co-pending application Ser. Nos. 09/961,080, filed on Sep. 20, 2001, and 09/961,079, also filed on Sep. 20, 2001, all of which have common inventorship with but different assignment than the present application, the full disclosures of which are incorporated herein by reference.
The designs described in the issued patent and copending applications have numerous advantages. The microneedles are delivered in a direction which is substantially perpendicular to the axis of the catheter, thus maximizing the depth of needle penetration into the wall and reducing trauma and injury. Moreover, by locating the needles on the exterior of an expanding involuted surface, the needles can be injected into tissue fully up to their point of attachment to the catheter, further maximizing the needle penetration depth which may be achieved.
Such deep needle penetration depends at least partly, however, on having an expansible surface structure chosen to accommodate the size of the lumen being treated. As lumen sizes may vary significantly, it may be necessary to maintain an inventory of differently sized catheters to address all patients and conditions.
While functional, the need to maintain and manufacture an inventory of catheters with differently sized balloons is costly. Moreover, should the physician choose the wrong balloon for a procedure, it may become necessary to replace the balloon with a second balloon catheter, further increasing the cost and time necessary to perform the procedure.
For these reasons, it would be desirable to provide improved devices and methods for transmitting appositional force from one side of a catheter-based balloon to the other opposite side. In particular, it would be desirable to provide intravascular and other intraluminal catheters having balloons or other inflation structures for advancing needles and other tools toward or into adjacent luminal walls, where the inflation structures are selectively inflatable to different sizes in order to accommodate different luminal diameters and/or to penetrate needles to different depths. Preferably, such selective inflation would be accomplished by delivering different pressures or volumes of inflation media to the inflatable structures. It is a further objective that the methods be simple and economic to implement and be useful with a wide range of vascular and other medical catheters. At least some of these objectives will be met by the inventions described hereinafter.
2. Description of the Background Art
Catheters used to slide microneedles through vessel walls are described in U.S. Pat. No. 6,547,803, issued on Apr. 15, 2003, and in co-pending application Ser. Nos. 09/961,080, filed on Sep. 20, 2001, and 09/961,079, also filed on Sep. 20, 2001, all of which have common inventorship with but different assignment than the present application, the full disclosures of which are incorporated herein by reference.